1. Field of the Invention
Embodiments of the present invention relate to a visual wear indicator for indicating wear in footwear and other articles.
2. Description of the Related Art
Footwear for athletics is a multi-billion dollar industry. Vast amounts of resources are spent developing footwear that is compatible with the biomechanics of the foot, leg and back so that the shoes absorb much of the stress exerted on the body during athletic activity. As different athletic activities exert different stresses on the body, most athletic activities now have footwear that has been specifically designed for that activity.
When new, contemporary athletic shoes are effective in reducing stress on the body. However, athletic shoes tend to wear down over time with normal usage. For example, the constant impact and shear forces on the bottom outer sole against the athletic surface tends to wear away the outer sole. Moreover, the forces exerted between the foot and the cushioning support within the athletic shoe during use tend to flatten and wear down the cushioning support. Once an athletic shoe wears down, its biomechanical compatibility and stress reducing capabilities greatly decrease. Continued use at this point may result in pain or injury. While it is of course possible to replace shoes before they become too worn, it is not always apparent when that point is reached, and often shoes are discarded when they are still effective in absorbing stresses.
Some athletic shoe wear indicators are known in the art. For example, U.S. Pat. No. 6,922,916, entitled “Footwear With Outsole Wear Indicator,” discloses a wear indicator for a footwear outsole. The wear indicator includes a plurality of strata that each have different properties, such as color. As portions of outsole are worn away, corresponding portions of an underlying stratum are revealed, thereby providing a wearer with the ability to determine the amount of wear that has occurred in an outsole. Such solutions are ineffective in revealing the breakdown of the cushioning support with the athletic shoe.
Another attempt at a footwear indicator is disclosed in U.S. Pat. No. 6,578,291, entitled “Shoe Wear Indicator.” The invention provides a shoe having a built-in, electronic wear indicator device capable of signaling (a) extent of shoe sole wear, (b) loss of ability to cushion and absorb shock, and (c) need to replace the shoe. The wear indicator device comprises (a) a sensor and microprocessor which can measure and report the use history of the shoe, (b) a wear indicator display which shows the consumer the current point in the shoe's life cycle and (c) a power source. The wear indicator device is installed between the midsole and outsole during the manufacturing process. Electronic solutions such as these tend to be expensive, fragile and environment dependent. For example, when used in climate conditions, the sensors often yield different readings. Moreover, such systems may malfunction in the rain or if the sensor or microprocessor gets wet.
Wear indicators have also been used in other industries, such as for example with automobile tires. Two examples of patents relating to such devices are disclosed in U.S. Pat. No. 3,578,055, entitled, “Tread Wear Indicator,” U.S. Pat. No. 3,929,179, entitled, “Indicator Device for Indicating Tread Wear and Tire Incorporating the Indicator.”